This invention relates to wireless data communication systems. Such systems are currently used in retail stores, warehouses and health care facilities to enable communication between a central data processing system and fixed or portable terminal units. Such units typically include point-of-sale terminals, personal computers, laptop or notebook personal computers, smaller pen terminals, personal communicators and bar code scanners. One such system which is currently available is the Spectrum 24 System, available from Symbol Technologies, Inc., assignee of this application. The Spectrum 24 System is designed to conform to the IEEE Standard 802.11 and provides a wireless local area network which operates in the 2.4 GHZ frequency band using frequency-hopping, spread-spectrum signaling format. A typical system will include at least one, and typically more than one access point, each of which is capable of providing full duplex data communication to a plurality of associated mobile units and communicating data between those units and a central processor over a wired network. Data communication is provided over 79 discrete frequency channels, with each access point having a unique frequency hop pattern among those channels, selected from 66 hop sequences at a hop-rare of 10 hops per second, wherein the hop sequence is separately synchronized by each access point. The system uses GFSK modulation for data transmission at a data rate of 1 Mbps per channel.
This invention also relates to paging systems, wherein a user is provided with a small, palm-size receiver that responds to a broadcast signal and receives a data message, usually comprising a telephone number to be called by the user. Enhanced paging systems may also provide alphanumeric data messages.
In a business environment using a wireless data communication system, it is possible to send page-like messages to wireless computer terminals. One such system is described in U.S. Pat. No. 5,459,458, wherein there is described a system utilizing wireless communication between a single central station and terminals, such as personal computers, portable computers, notebook computers, personal intelligent communicators, portable wireless terminals and the like, wherein the terminals are programmed to provide a 1virtualk paging function.
Further, U.S. Pat. No. 5,115,233 describes a system wherein such terminals are arranged to provide voice communication with the central station. As described, data communications are interrupted to enable the system to enter a voice communication mode.
The known systems provide a sophisticated level of data communication, enabling the user of a mobile terminal to manually enter data via a keyboard for communication to the central processor. In many cases it is impractical to provide a sophisticated mobile terminal unit to every employee because of cost considerations, and it is often inconvenient to require a user to carry about a bulky terminal, when only limited message communications are required for the particular user to carry out his or her duties.
It is therefore an object of the present invention to provide highly portable and simplified data communication devices for use in conjunction with a wireless data communication network, Such devices may be simplified paging devices, or may be message units that provide a paging function as well as limited and specific data communications from the user to the central station to signal time card transactions, emergencies, etc. In one embodiment the mobile unit provides voice messaging or voice communications over the data channel without interrupting the normal data handling routine. In another configuration the system can provide added paging communications to a portable bar-code scanner, to enable message signalling to the user. In a still further embodiment, the user can be provided with a message on a separate high-resolution display.